1. Technical Field
The present disclosure relates to a thin film transistor array substrate and to a method of manufacturing a thin film transistor array substrate for a display panel, and more particularly, to a thin film transistor array substrate and to a method of manufacturing a thin film transistor array substrate for a display panel capable of reducing the number of steps in a mask process.
2. Description of the Related Art
In general, a liquid crystal display device displays an image by adjusting the transmittance of a liquid crystal material using an electric field. For this purpose, the liquid crystal display device may include a liquid crystal display panel in which the liquid crystal cells are arranged in a matrix pattern, and a driving circuit for driving the liquid crystal display panel.
The liquid crystal display panel may include the thin film transistor array substrate and a color filter array substrate facing each other, a spacer located for fixedly maintaining a cell gap between two substrates and a liquid crystal injected into the cell gap.
The thin film transistor array substrate may include gate lines and data lines, a thin film transistor formed as a switching device at every crossing of the gate lines and the data lines, a pixel electrode connected to the thin film transistor substantially defining a liquid crystal cell, and an alignment film applied to the substrate. The gate lines and the data lines receive signals from the driving circuits through each of their respective pad parts. The thin film transistor, in response to a scan signal supplied to a gate line, supplies to the pixel electrode a pixel voltage signal applied to the data line.
The color filter array substrate may include a color filter formed to correspond to the liquid crystal cells, a black matrix for reflecting external light and separating the color filters, a common electrode for commonly supplying a reference voltage to the liquid crystal cells, and an alignment film applied to the substrate.
The liquid crystal display panel may be fabricated by combining the thin film transistor array substrate and the color filter array substrate which are separately manufactured, injecting the liquid crystal material between the substrates, and sealing the substrates having the liquid crystal material between them.
In such a liquid crystal display device, thin film transistor array substrate fabrication may involve a semiconductor process which requires a plurality of mask processes, thereby complicating the manufacturing process. This may be a major factor in the manufacturing cost of the liquid crystal display panel. To solve this, a thin film transistor array substrate has been developed with the goal of reducing the number of steps used in mask processes. This is because one mask process may include a plurality of sub-processes such as, for example, thin film deposition, cleaning, photolithography, etching, photo-resist stripping, inspection processes and the like. Recent development efforts have resulted in a four-round mask process that eliminated one mask process from an existing five-round standard mask process.
As described above, conventional thin film transistor array substrates and manufacturing methods thereof adopt a four-round mask process, thereby reducing the number of steps in the manufacturing processes in comparison with the five-round mask process and hence reduces manufacturing cost accordingly. However, as the conventional four-round mask process may still be a complex manufacturing process which may limit the reduction of the manufacturing costs associated with manufacturing thin film transistor array substrates, there is a still a need in the art for an approach that is capable of further simplifying the manufacturing process and further reducing the manufacturing costs associated with manufacturing thin film transistor array substrates.